There are many answer about the best time for equilibrium between the radon and radium. If any equation about that.
Good afternoon Murthada,
The widely accepted approach in parent-daughter nuclide systems where T 1/2 (parent) >> T 1/2 (daughter) is 5 times the T 1/2 (daughter).
For Rn-222 T 1/2=3,8232 d => 19.116 days
In normal laboratory practice the samples containing Ra-226 are left sealed to prevent Rn-222 escape for 3 weeks.
Kind regards,
Pawel
As we now , the half life of Rn-222 is 3.8 d
for experimental work it is better to sealed the samples included Ra-226 for a period 3-4 weeks to prevent Rn-22 from escape
To achieve complete equilibrium between radium and radon 30 day is need in a good sealed housing. T assure this use the Eq. {ARn/ARa=(1-exp(-Lamda*t) and plot a relation between LHS with different (t) you get LHS=1 after 30 day/
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1 Recommendation
Yasser Ebaid
Fayoum University
The best is 4 weeks. For example at 20 days you wil have equilibrium only at 97.35 %
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1 Recommendation
P. Gaca
University of Southampton
@Yasser and Ahmed
Agereed. with your comments.
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2 Recommendations
Murtadha Sh. Aswood
University of Al-Qadisiyah
Thank you for all
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Mostafa Yuness Abdelfatah Mostafa
Minia University
you can check 99% within 600 h nearly 26 days 4 week is the best
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A. Chetaine
Mohammed V University of Rabat
the best time is 21 days if the system (radon and radium) is sealed
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1 Recommendation
C. Ningappa
Vidya Vikas Educational Trust
4 week is the best
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Laith Najam
University of Mosul
The best time to equilibrium between radon and radium is 4 weeks
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Joseph L Alvarez
Alpha Beta Gamut
The ratio of radon to radium in a sample after processing (cleaning, drying, ..., sealing in a container) varies with the sample and processing techniques. Often the ratio may be 50% or more radon to radium. Time to near equilibrium will vary.
The best way to determine the sample holding time is to measure the sample at various times after placing in a sealed container. A holding time of 30-days/4-weeks is best, as others have stated. A shorter holding time can be justified by measuring the ingrowth.
A shorter holding time may be required for a fast turn around. The reduced holding time must be documented as adequate. A time to equilibrium study should be made periodically to ensure that the sample processing and sealing produces adequate equilibrium in the specified holding time.
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6 Recommendations
Carlos Sainz
Universidad de Cantabria
Agree with Joseph L Alvarez. Experimental ingrowth measurement is the best approach to determine the time to equilibrium.
Sometimes, the initial radon concentration in a solid sample is not zero after processing, mainly because an amount of radon can be present in the grains of the material. In these cases, initial equilibrium can be rather high, and the time needed for secular equilibrium between radon and radium can be significantly lower than 4 weeks.
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2 Recommendations
Riaz Akber
Safe Radiation
Rn-222 to Ra-226 equilibrium is a complex issue. In nature, ground exhales a very small proportion of radon from a depth of a few metres into the air above, but any Ra-226 suspension is only from the surface. For this reason, ambient air generally would have more Rn-222 activity per unit volume than Ra-226. In the soil (depending upon the profile depth) Rn-222 and Ra-226 remain close to secular equilibrium. Groundwater carries dissolved Rn-222 and, depending upon soil solute interaction parameters, some Ra-226. Some materials, such as charcoal, will preferentially adsorb Rn-222, etc. Laith, Joseph and Carlos are right that, if a sample is isolated and subject to treatment, then a secular equilibrium is likely to reach between Ra-226 and Rn-222 in 5 or more Rn-222 half lives. Regarding gamma spectroscopy, for activity concentration of NORM isotopes, there are some reported methods to estimate values without Rn-222 equilibrium waiting time. They are based on estimating U-235 using gamma peaks other than 186 keV. You may directly search for them, or feel free to drop me an email on [email protected] and I may send you some references. Regards Riaz
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2 Recommendations
Robert Frantisek Holub
Clarkson University
Make sure there is no leak. Leak rate is added to decay rate, which shortens the waiting time to reach equilibrium between Ra and Rn. Checking for leak can be done by putting the can into a larger container and measure if there is any Rn activity build up in the larger container.
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1 Recommendation
Octavian G Duliu
University of Bucharest; Geological Institute of Romania
Usually one month is enough provided that the sample is hermetically sealed in an appropriate vial, preferably made of aluminum (plastics are sometime porous and radon can diffuse)
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2 Recommendations
M. F. Attallah
Egyptian Atomic Energy Authority
To be sure you have equilibrium between Rn-222 and Ra-226. You have to leav a sealed bottle (including your sample) for at least 7 half-life of Rn (3.8 day), it means you have wait about 28 day. After that, it will found equilibrium between daughter (Rn-222) and its parent Ra-226. Make sure there is no leak.
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7 Recommendations
Ali Abdulwahab Ridha
Al-Mustansiriya University
27 DAYS OR MORE
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Ali Abdulwahab Ridha
Al-Mustansiriya University
27 day
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1 Recommendation
Karina Moreno
Universidad Politécnica de Madrid
Hay alguna fórmula que determine este tiempo?
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I have a relevant question about a very specific situation. What if two samples for which secular equilibrium is attained, are combined!! Does the secular equilibrium still holds?? or one have to keep the new composite sample sealed for another month for secular equilibrium??
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Joseph L Alvarez
Alpha Beta Gamut
Ahmad Ali
Yes. Combining two samples at equilibrium will release radon. The amount of radon lost will depend on the matrix and the method and time of combination.
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د.باقر فليح عبد الحسن
University of Al-Qadisiyah
Thank you very much for this valuable information
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M. Shakir Khan
Majmaah University
The detailed article is attached here for the same.
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1 Recommendation
Laith Najam
University of Mosul
27 day
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1 Recommendation
Hala Jasim
University of Mosul
متابعه
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Mohamed Saad Seoud
Ministry Of Health - Kuwait
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Bakhodir Saidullaev
Institute of Nuclear Physics, Uzabekistan, Tashkent
Who has the time an article on the equilibrium between of Radon and Radium?
If so, please share it with me.
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1 Recommendation
Abdalsattar Kareem Hashim
University of Kerbala
The time required for long- term radioactive equilibrium between radon and radium is approximately 27.3 days.
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Octavian G Duliu
University of Bucharest; Geological Institute of Romania
About four weeks
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Hala Jasim
University of Mosul
About 4 weeks
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